There is often a need to scribe lines from the edge of a piece of lumber or sheet material at a predetermined angle. For example, in framing a roof, the roof rafters must have their ends trimmed so as to establish the pitch angle of the roof to be constructed.
U.S. Pat. No. 4,138,914 issued on Feb. 13, 1979 for a "Saw Guide Apparatus" shows an adjustable saw guide useful for such purpose.
It is sometimes necessary to match an angle existing between two members in order to scribe the same angle on a workpiece. In such cases, any device used for this purpose must be able to be insertable between the members to be adjusted in conformity with the angle existing between these members.
Such guides and adjustable angles are often used for scribing lines on sheet material such as plywood, glass, drywall, etc. preparatory to cutting the same at a predetermined angle between the side edge of the sheet material.
U.S. Pat. No. 4,955,141 issued on Sep. 11, 1990 for "An Adjustable Pivot Angle Square Invention" describes such a general purpose adjustable angle device in which two elongated members are pivotally mounted to each other at one end and with a connecting member pivotally connected at one end to one of the members and sliding within an elongated slot formed in the other member. As the connecting member moves along the slot, varying adjustable angles are formed between the first two pivotally connected members.
See also U.S. Pat. No. 1,906,988 issued on May 2, 1933 for a "Measuring Apparatus" similarly showing a slotted member pinned at one end to a second elongated member with a connecting member pinned to the second member, and having one end attached to a slider moving through the slot. This enables a setting of an angle between the first and second mentioned members.
In each case, the devices are not readily adjustable through a full 360.degree. rotation. In the case of U.S. Pat. No. 1,906,988, an interference is created between the second and third members, while in U.S. Pat. No. 4,955,141, an interference similarly is encountered necessitating a reversal of the adjustment rotation and a reorientation of the device in order to carry out a 180.degree. adjustment capability. The device shown in U.S. Pat. No. 4,955,141 is not practically useable as an angle measuring apparatus since a projecting corner is created at each apex of the pivotally joined members preventing a flush interfitting within angled members to be measured, and also creating saw guide interference at the end of the guide.
It is sometimes necessary to provide a guide which extends for considerable distances as in the case of using the device to scribe or cut across large pieces of sheet material. In such instances, neither of these prior art devices described above are able to be effectively used for spanning such larger distances, necessitating an approximation of a scribe line or clamping of a secondary guide member to the piece to be cut or scribed.
When such devices are used as a saw guide, a base member must be held against the lumber piece or other material being cut as the saw is advanced across the angled member with the base member being held in an accurately determined positioned as the sawing operation is continued. Oftentimes there is some slight shifting movement resulting from the urging of the saw edge against the member used as the guide, with a resultant loss of accuracy in the cut.
Accordingly, it is an object of the present invention to provide an adjustable guide and angle finder device which is capable of adjustment through a full 180.degree. or even 360.degree. rotation in a single direction of adjustment without requiring reorienting the device to achieve an angle adjustment through the complete 360.degree. range.
It is a further object of the present invention to provide such a device in which an uninterrupted contour is maintained at the apex of the angled members to allow use of the device as an angle finder by being interfit flush against the angled members, and to preclude any interference with a saw being moved anywhere along the angled member edge.
It is still another object of the present invention to provide such an adjustable angle device in which the device is able to be secured to the member on which an angle is being cut or scribed such as to eliminate the need for manually holding the angle against the member during scribing, saw cutting, etc.
It is yet another object of the present invention to provide such a device which is adaptable for use across relatively large distances.